A fluid‑like substance called synovial fluid lubricates the surfaces where bones meet in joints, making the coefficient of static friction between bones very small. For simplicity, assume the surfaces in the knee are flat and horizontal.   Why is the minimum force required for initiating movement of bones in a typical knee joint different for different people, in spite of the fact that their joints have the same coefficient of static friction?

Q: The jib crane is designed for a maximum capacity of 7 kN, and its uniform I-beam has a mass of 250…

A: Given: The mass of the beam is m=250 kg

Q: ea of a raindrop to be 1.2 kg/m³.

A: Given: diameter of spherical raindrop 1.9 mm Vertical distance is 5000 m

Q: A spherical raindrop of mass 0.0128 g and radius 1.45 mm falls from a cloud that is at a height of…

A: The expression for terminal speed is vt=2mgCρA=2mgCρπr2 Substitute vt=20.0128×10-3 kg9.81 ms20.61.3…

Q: 2 - A circular disk (with a semi-circular cutout) is supported by two walls and cable AB. The weight…

A: Solution: A circular disc with a semicircular cutout is supported by a frictionless wall with…

Q: Examine different types of shoes, including sports shoes and thongs. In terms of physics, why are…

A: A sport shoe contains the different type of pattern on the bottom.

Q: 21.82 •• CP A small sphere with mass m carries a positive charge q and is attached to one end of a…

A: The electric field of infinite sheet is  E=σ2ε0 where σ is the conductivity and ε0 is the…

Q: A skate park is formed by two semicircles of radius R1 = 8.3 m and R2 = 1.0 m and a flat central…

A: Given  R1 = 8.3 m  R2 = 1.0 m length of flat part  = L = 3.6 m. The semicircles are tangent to the…

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A:

Q: The block shown in (Figure 1) has a mass of m= 90 kg, a height H = 1.8 m, and width L = 2.4 m. It is…

A:

Q: The direction of the frictional forces is something you need to think about carefully. The best rule…

A: Since when a force pressed the book against the wall, then to hold its (position of the book) the…

Q: Two ends of the string are fastened at two corners of a picture frame weighing 200 N which are 60 cm…

A: Given: W=200N, d=60cm, L=70cm Refer to the free-body diagram below :

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A:

Q: 600 N 300 300 F B E 120 N-m 60° 60 A 200 400 200 Dimensions in millimeters termine the magnitude of…

A: The free body diagram of the problem is shown below,

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A: Consider that the spool undergoes pure rolling. So, calculate the moment of inertia of the spool…

Q: The two blocks (m = 13 kg and M = 90 kg) in the figure are not attached to each other. The…

A: Mass of block, m =13 kg Mass of block, M = 90 kg The coefficient of static friction μs=0.44

Q: If the coefficient of friction between the steel wedge and the moist fibers of the newly cut stump…

A:

Q: The net interatomic force between the atoms of an element is given by the following expression:…

A: The interatomic equilibrium distance, r is 3 Å. Write the expression to calculate the interatomic…

Q: 9.3 m 12 m ➖➖➖➖➖➖➖➖ Firefighter 8.4 m up ladder X cm 1/3 up the ladder 2. As an extension of sample…

A:

Q: Two molds of mass, the first m1 = 1.0 and the second, m2 = 2.0 kg, touch each other on a horizontal…

A:

Q: Find the constant force with the least magnitude that must be applied to the board in order to pull…

A:

Q: A SEWAGE WORKER is inside a large underground aqueduct (diameter >> a man's height) of circular…

A:

Q: A mixing beater consists of three thin rods, each 10.9 cm long. The rods diverge from a central hub,…

A:

Q: Problem A block of mass m is placed on a rough surface inclined relative to the horizontal. The…

A:

Q: A rectangular plate is supported by three cables as shown. Knowing that the tension in cable AB is…

A:

Q: When a person stands on tiptoe (a strenuous position), the position of the foot is as shown in…

A: Normal force reaction of weight of person on the toe: n = 720 N Distance of R to toe: dR = 18 cm =…

Q: Q 2: In the system shown in the figure. When a vertical force F=500N acts on the point A, determine…

A: Concept used: Frictional force acts in direction opposite to direction of motion.

Q: A useful instrument for evaluating fibromyalgia and trigger-point tenderness is the doloriometer (or…

A: Calculate the area of the circular probe. A=π4d2A=π4(1.44 cm×1 m100 cm)2A=1.6286×10−4 m2

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A:

Q: Determine the force P required to maintain the 165-kg engine in the position for which 0 = 36°. The…

A:

Q: If the coefficient of friction between the steel wedge and the moist fibers of the newly cut stump…

A:

Q: A toddler weighs 10 kg and raises herself onto tiptoe (on both feet). Her feet are 8 cm long with…

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Q: A 550 g squirrel with a surface area of 920 cm2 falls from a 5.6-m tree to the ground. Estimate its…

A:

Q: You decided to go to SM to buy a new pair of shoes. Upon picking the new pair of shoes you tried…

A:

Q: The block shown in (Figure 1) has a mass of m= 100 kg, a height H=1.4 m, and width L=2 m. It is…

A: Torque is the product of force and lever arm distance.

Q: Determine the x- and y-coordinates of the centroid of the shaded area. Input values in two (2)…

A:

Q: A small box of mass m1m1 is sitting on a board of mass m2m2 and length LL (Figure 1). The board…

A: A small box of mass m1 is sitting on a board of mass m2 and length L. The board rests on a…

Newton's Second Law

Newton’s laws of motion describe the relationship between the motion of an object and forces acting on it. Newton’s law of motion has two types as follows: